Electric circuit breaker



s. B. WOOLARD 2,380,817

ELECTRIC CIRCUIT BREAKER I I Filed'April 25, 1943 -2 Sheets-Sheet. l

July 31, 1945.

Inventor: Simon B.Woo|a1-d, b9 $17M 7 His Attovneg.

/ u ll y 31, 19 5 s. B. WOOLARD 2, 8

ELECTRJ IC CIRCUIT BREAKER Filed April 25, 1943 2 Sheets- Sheet 2 Fig.2.

Inventor: Simon BWoolar'cl, b9

His Attovneg.

Patented July 31, 1945 ELECTRIC CIRCUIT BREAKER Simon B. Woolard, Schenectady, N. Y., asslgnor to General Electric Company, a corporation of New York Application April 23, 1943, Serial No. 484,231

2 Claims. (Cl. 200-148) My invention relates to electric circuit breakers, and more particularly to circuit breakers of the fluid blast type. Specifically, my

invention is an improvement on United States Letters Patent 2,298,778-Thumin and Boisseau, granted October 13, 1942, and assigned to the same assignee as the present application.

' As the capacity of circuit breakers is increased, the conducting parts of such circuit breakers, from which the heat generated by current traversing these parts is dissipated simply by radiation, or conduction to other parts, must necessarily increase in size particularly with increase in current ratings with the consequent result that the dimensions and mass of such circuit breakers become very large. Such increase in mass of the moving parts of a circuit breaker introduces difliculties when high speed operation thereof is desired, since the large masses necessitated by the high current ratings require correspondingly large acceleration forces.

In circuit breakers of the type disclosed in Rankin Patent 2,306,186 granted December 22, 1942, and assignedto the same assignee as the present application. there is disclosed a high voltage electric circuit breaker which utilizes the increased dielectric strengthof gas under pressure during interruption so as to minimize the danger of restriking of the arc within the interrupting chamber. In such a circuit breaker, after the arc is interrupted and the valve which controls the fluid blast is closed the high pressure fluid remaining in the fluid lines and the cylinder of the operating piston must drain off through the nozzles and out through the exhaust chamber. This requires a relatively long time so that the pressure on the contact opening piston does not permit the contacts to close in a short enough period of time for high speed reclosing. This is also true of the fluid blastcircuit breaker disclosed in copending application Serial No. 495,746, filed July 22, 1943Flurscheim, now Patent 2,367,934, assigned to the same assignee as the present application.

It is an object of my invention to provide a new and improved fluid blast circuit breaker in which the structure is small and light enough for. economy and rapid acceleration and heavy enough to carry its continuous rated current within the permitted range of temperature rise.

Itis another object of my invention to provide anew and improved circuit breaker of the fluid blast type provided with means which permit high speed reclosing thereof.

Still another object of my invention is to provide a new and improved circuit breaker comprising a three-way blast valve which under normal current carrying conditions of the circuit breaker, permits the movable parts of the circuit breaker to be subjected to the effects of a continuous cooling current of fluid such as air.

Further objects and advantages of my inven- 'tion will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawings, in which Fig. 1 is a schematic diagram partly in section illustrating one form of my invention as applied to an axial blast type of fluid blast circuit breaker, while Fig. 2 illustrates a modification of my invention as applied to a cross blast type of circuit breaker.

. In Fig. 1 I have illustrated my invention as applied to a circuit breaker of the axial blast type such as was disclosed and claimed in the above mentioned Rankin patent. It should be understood that my invention is equally applicable to other types of circuit breakers, although it is especially applicable to fluid blast circuit breakers of the type disclosed and claimed in the above mentioned Rankin patent and in the copending Flurscheim application referred to above.

Referring now to Fig. 1 of the drawings, the numeral In indicates generally a circuit breaker of the type disclosed in the above mentioned Rankin patent. This circuit breaker comprises an interrupting head H the structural features I of which are shown in section in order that these features which are somewhat schematically shown, may become apparent. These structural features form no part of my present invention and are disclosed and claimed in the above mentioned Rankin patent. The interrupting head or unit I I includes a pair of relatively movable contacts l2 and I3, the former being a retractable pin contact while the latter is a stationary contact. Preferably the retractable pin type contact I! is suitably connected to a fluid motor which I have illustrated as comprising a piston I mounted for reciprocal movement in a. cylinder I5. Suitable biasing means such as a spring I6 may be provided for constantly urging retractable pin type contact l2 to the closed position to engage stationary contact I 3. V

In order to complete the electrical circuit through interrupting head ll, retractable pin type contact I2 is electrically connected to a terminal H as by means of a flexible lead It while stationary contact II is electrically connected to a suitable terminal I. Terminal i1 is suitably connected to a line conductor 20 while terminal I! is connected to a line conductor 2|. It should be understood that a plurality of interrupting heads such as it may be serially arranged between lines 2| and 2| and a suitable disconnecting contact may also be provided as is disclosed in the above mentioned Rankin patent.

The contacts l2 and II of interruptin unit or head II are separable within an interruptin chamber 22 which in the present instant is elongated and formed of a mechanically strong insulating material. This chamber is mounted within a suitable insulating column 23 provided with a weatherproof hood 24. Interrupting head II is provided with a restricted nozzle formed by an annular valve-like control member 25 guided in sleeve-like manner for limited vertical rectilinear movement around cylinder II. This member 25 is biased to its normal lower position by springs 28. Member "provides a restricted annular exhaust port or nozzle arrangement whichmay be increased somewhat under abnormally high pressures although in the usual operation the springs 28 maintain the venting area of the port substantially fixed and uniform.

The contacts l2 and ll of interrupting head or unit II are separated by introducing fluid under pressure from a source 28 into insulating chamber 22. Upon introduction of such a blast 'of fluid, piston. H is moved upwardly moving contact l2 at the same time and the arc drawn between contacts l2 and I2 is extinguished by the axial blast of fluid surrounding the arc. The restricted exhaust port which is defined at least in art by annular member 2| causes a relatively h eh pressure in chamber 22 thus forming an eifective dielectric to prevent restriking of the are after interruption thereof. Heretofore as the fluid under pressure gradually leaked out of the port defined in part by annular member 25, the pressure was reduced sufnciently so that spring I! caused retractable pin type contact I 2 to reengage stationary contact it. However, an appreciable time elapsed for thi pressure to gradually dissipate through the restricted port, which for high speed reclosing, may be undesirable.

My invention is particularly concerned with a new and improved arrangement permitting this fluid under pressure to be dissipated rapidly to permit high speed reclosing without impairing the effectiveness of the restricted exhaust or "conserved pressure" type of fluid blast circuit breaker. To this end, I have provided a new and improved blast valve generally indicated at 29 which interconnects source of fluid under pressure 2! with a conduit 30 including an insulating section II which in turn is connected to chamber 22 of interrupting head Ii. Blast valve 22 isof the pilot-operated type and in many respects is very similar to the blast valve disclosed in .United States Letters Patent 2,315,991--Thumin, granted April 6, 1943, and comprises a valve member 22 which is adapted to seal against a seat 33 and control the flow of fluid between source 28 and interrupting head ll. Valve member 22 is connected by a suitable valve stem 24 to a piston 35, reciprocatingly mounted in the cylinder 36. A suitable spring 31 biases valve member 32 to the closed position although it will be obvious that fluid under pressure from source 2! also aids in maintaining this valve in the closed position. Opening of blast valve 29 so as to cause valve member 32 to move away from seat 32 is accomplished through operation of a pilot valve 2| which permits fluid under pressure from source 28 to how through a conduit II to the left-hand end of cylinder 36. Since the area of piston 25 is considerably larger the area of valve member 22 high speed opening of blast valve 29 is obtained. Any suitable means for operating pilot valve II (not shown) may be provided, A suitable spring 40 biases pilot valve 22 to the closed position, and when in the closed position, the portion of cylinder 28 to the left of piston 35 is vented to atmosphere through an opening ll. The blast valve described thus far is not my invention but is disclosed in the above mentioned Thumin Patent 2,315,991.

In order that the fluid under pressure contained in chamber 22 and in the iluld passageway com- I prising conduits 30 and II may be reduced rapidly upon interruption of the circuit after blast valve 29 is closed, thereby permitting high speed reclosing of circuit breaker l0, blast-valve 29 is constructed as a three-way blast valve, in that the end of cylinder 28 to the right of piston 25 as shown in Fi 1 is connected to atmosphere through a relatively large orifice or port 42 and is also connected with conduit "through another relatively large orifice or port 43. Consequently when blast valve 29 is closed as shown in Fig. 1, any fluid under pressure remaining in conduits 30, 3i and in are chamber 22 will be quickly vented to atmosphere through the opening or port, thereby permitting high speed reclosing oi the circuit breaker. It should be understood that port 42 does not open until it is no longer necessary to maintain a predetermined pressure around contacts i2 and I3 after circuit interruption. Without port 42 this pressure would take an appreciable time to dissipate and reclosing of contact 12' would not occur in time to permit high speed reclosing.

The three-way blast valve 2! also permits the current carrying capacity of circuit breaker in efl'ect, but it should be understood that a suitable blower or the like, such as is disclosed in the Thumin and Boisseau patent referred to above, may be provided. This cooling stream of air surrounds movable contact II whenever blast valve 29 is in the position indicated in Fig. 1. As soon as blast valve 20 is opened piston 2| closes orifice 43 so that fluid under pressure from source 22 cannot escape, and consequently the eflectiveness of this fluid blast for arc-extinguishing purposes is not impaired.

In addition the ventilation of arc chamber 22 by virtue of the chimney effect gives under normal ambient conditions moving air which will absorb and carry off moisture that might have condensed on the inner walls of arc chamber 22. In this way a drying action is obtained.

In view of the detailed discussion included above the operation of circuit breaker ID will be obvious to those skilled in the art and no further description will be included herewith. BY

cooling the movable conducting parts of the air blast circuit breaker in the manner indicated, not only is high speed operation of high current carrying capacity circuit breakers made possible, but many economic advantages are also obtained. For example, the overall dimensions of the circuit breaker may be considerably reduced and the cost and the space occupied are accordingly diminished. In addition to the cooling feature, the venting feature which permits high speed reclosing is also very desirable.

Although I have illustrated my invention in Fig. '1 as applied to an axial blast type of circuit breaker in which high pressure fluid is used as an insulating dielectric to prevent restriking-of the are after circuit interruption, with which my invention is especially applicable, insofar as the cooling feature of my invention is concerned, it is also applicable to fluid blast circuit breakers of the cross-blast type, and in Fig. 2 such an application is illustrated. By using my new and improved three-way blast valve 29, no other means for permitting cooling air to enter the arc chamber is required as in prior art arrangements.

In Fig. 2 I have illustrated my invention as applied to a circuit breaker of the cross fluid blast type such as disclosed and claimed in United States Letters Patent 2,284,842--Prince et al., granted June 2, 1942 and assigned to the same assignee as the present application. The corresponding parts of the. blast valve of the circuit breaker generally indicated at 44 in Fig. 2 are designated by the same reference numerals as in Fig. l. The circuit breaker 44 includes relatively movable contacts comprising a stationary contact 45 and a movable contact blade or rod 46 arranged to be operated to draw an arc in arc chute 41, the entire unit being suitably mounted on an insulator 48. Upon separation of contacts 45 and 46 an arc is drawn in arc chute 41 and a blast of fluid from source 28 controlled'by blast 29 issues from conduit 30 into arc chute 4'! so as to force the are against the edges of a plurality of partitions or ballles 49 which are transverse of the arc gap and the ends of which extend close to movable contact 46, When the blast valve 29 is in the closed position indicated in Fig. 2, a cooling fluid enters orifice 42, passes through the righthand end of cylinder 36, orifice 43, and conduit 30, so as to cool the current carrying parts of circuit breaker 44. The operation of the circuit breaker of Fig. 2 will be obvious to those skilled in the art and no further description thereof will be included.

While I have illustrated specific embodiments of my invention, it should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated and that changes and modifications may occur to one skilled in the art without departing from the spirit and scope of my invention. I aim in the appended claims to cover all such changes and modifications.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a fluid blast circuit interrupter comprising relatively movable contacts, a source of fluid under pressure, a fluid passageway including a piston operated blast valve associated with said source for producing a blast of fluid adjacent said relatively movable contacts for arc-extinguishing purposes during the circuit opening operation of said circuit breaker, means including an opening to atmosphere in said blast valve effective when said blast valve is closed rapidly to vent said fluid passageway, and means including said piston for efiectively closing said opening to atmosphere when said blast valve is opened so that the efiectivenss of said fluid blast during a circuit opening operation is not impaired.

2. In an electric circuit breaker of the fluid blast type comprising relatively movable contacts one of which is biased toward the closed circuit position, an operating piston connected to said biased contact, an arc extinguishing chamber for housing the 'are drawn upon separation of said relatively movable contacts, a source of fluid under pressure, means including a fluid passageway and a blast valve including a piston for operating the same associated with said source for supplying fluid from said source to said operating piston and said chamber, means for conditioning said circuit breaker for high speed reclosing operation including an opening to atmosphere in said blast valve effective when said blast valve is closed rapidly to vent said fluid passageway so that said operating piston may permit said contact to move without delay toward the closed position immediately following a circuit interrupting operation, and means including said pistonfor operating said blast valvev for closing said opening to atmosphere when said blast valve is opened so that the efiectiveness of said fluid blast during a circuit interrupting operation is not impaired.

SIMON B. WOOLARD. 

